Collectors for recovering platinum group metals from spent catalysts, their preparation methods and applications

Abstract

This invention provides a collector for recovering platinum group metals (PGMs) from spent catalysts, its preparation method, and its application, belonging to the technical field of precious metal recovery. The collector comprises a copper matrix, a flux, a framework support, and a lattice activator: the copper matrix, flux, and lattice activator are loaded on the surface of the framework support; the copper matrix is ​​elemental copper or a copper-based compound; the flux is boric acid or a borate; the framework support is a porous inorganic material; and the lattice activator is tin, a tin alloy, or a metal sulfide. The collector serves as a collector for the pyrometallurgical recovery of PGMs from spent catalysts. This invention constructs a multi-component synergistic collector composed of a copper matrix, flux, framework support, and lattice activator, which significantly improves the recovery rate of PGMs, especially rhodium, from spent automotive exhaust purification catalysts in pyrometallurgical treatment, and reduces the smelting temperature required for pyrometallurgical treatment, thus significantly reducing energy consumption.

Description

Technical Field

[0001] This invention belongs to the technical field of precious metal recycling, and specifically relates to a collector for recovering platinum group metals from waste catalysts, its preparation method, and its application. Background Technology

[0002] Automotive exhaust purification catalysts are honeycomb-shaped, with cordierite as the carrier and a layer of γ-Al₂O₃ coated on the surface. The active components platinum (Pt), palladium (Pd), rhodium (Rh), and additives (CeO₂, etc.) are dispersed in the alumina coating. The platinum group metal content in waste automotive exhaust purification catalysts reaches 0.1% to 0.3%, making this catalyst a very important platinum group metal resource.

[0003] Metal smelting and trapping is a mainstream pyrometallurgical process for recovering platinum group metals (Pt, Pd, and Rh) from spent automotive exhaust catalysts. It features a short process flow, high enrichment ratio, and low environmental pressure. In this method, flux and base metal trapping agents are added to the spent automotive exhaust catalyst. During the high-temperature smelting and trapping process, the platinum group metals have a strong affinity for the trapping agent and enter the alloy phase of the agent, while the carrier forms the slag phase. Active base metals such as Ca, Mg, and Al also enter the slag phase. Commonly used trapping agents include lead, matte, copper, and iron, with copper being the most widely used. For example, CN119351769A discloses a method for efficiently enriching platinum group metals from spent automotive exhaust catalysts using copper, employing elemental copper or copper compounds as the trapping agent, achieving recovery rates of over 98% for Pt, Pd, and Rh. However, it has certain drawbacks, such as requiring ultra-high-temperature smelting at no less than 1400℃ and the addition of a large amount of slagging agent. Summary of the Invention

[0004] Therefore, the present invention aims to provide a collector for recovering platinum group metals from waste catalysts, a method for preparing the same, and its application, in order to solve at least one technical problem in the prior art.

[0005] This invention is implemented as follows:

[0006] The first aspect of the present invention provides a collector for recovering platinum group metals from waste catalysts, the collector comprising a copper matrix, a flux, a framework support, and a lattice activator;

[0007] In the aforementioned trapping agent, a copper matrix, flux, and lattice activator are loaded on the surface of the skeletal carrier;

[0008] The copper matrix is ​​made of elemental copper or a copper-based compound.

[0009] The flux is boric acid or borate;

[0010] The skeleton carrier is made of porous inorganic material;

[0011] The lattice activator is tin, tin alloy, or metal sulfide.

[0012] Furthermore, the weight percentages of each component in the raw material of the trapping agent are as follows:

[0013] Copper matrix: 50%~80%;

[0014] Flux: 5%~20%;

[0015] Skeleton carrier: 10%~30%;

[0016] Lattice activator: 1%~10%.

[0017] Furthermore, the porous inorganic material is selected from at least one of porous alumina, porous silica, alumina-silica composite porous microspheres, expanded perlite, and pumice.

[0018] Furthermore, the porous inorganic material has a D50 of 0.1 mm to 5 mm and a specific surface area of ​​not less than 20 m². 2 / g, porosity not less than 50%.

[0019] Furthermore, the porous inorganic material has a D50 of 0.5 mm to 2 mm and a specific surface area of ​​50 m². 2 / g~500m 2 / g, with a porosity of 60%~90%; pore size distribution range of 10nm~1000nm.

[0020] The second aspect of the present invention provides a method for preparing the above-mentioned scavenger for recovering platinum group metals from waste catalysts. The preparation method specifically comprises: mechanically mixing the copper matrix, flux, framework carrier and lattice activator into a uniform mixed powder; and performing heat treatment under a reducing or inert atmosphere at 600°C to 900°C.

[0021] Furthermore, the heat treatment specifically involves heating from room temperature to the target temperature at a rate of 1°C / min to 10°C / min under a reducing or inert atmosphere, holding at that temperature for 10 min to 60 min, and then cooling to room temperature.

[0022] A third aspect of the present invention provides the application of the above-described collector for recovering platinum group metals from spent catalysts, wherein the collector is used as a collector for pyrometallurgical recovery of platinum group metals from spent catalysts.

[0023] Furthermore, the specific steps of the pyrometallurgical method for recovering platinum group metals from spent catalysts are as follows:

[0024] After pulverization, the precipitant, reducing agent, and binder are added to the waste catalyst, mixed, and agglomerated.

[0025] Under a reducing atmosphere, smelting is carried out at 1200℃~1350℃ to form a copper-based alloy phase and a slag phase rich in platinum group metals;

[0026] The copper-based alloy phase and the slag phase are separated, wherein the copper-based alloy phase is enriched with platinum group metals.

[0027] Furthermore, the amount of the trapping agent is 5wt% to 15wt% of the spent catalyst;

[0028] The reducing agent is a carbonaceous reducing agent, and its dosage is 2wt%~8wt% of the spent catalyst;

[0029] The binder is an organic binder, preferably sodium carboxymethyl cellulose, and its dosage is 1 wt% to 5 wt% of the mixture of the waste catalyst, the scavenger and the reducing agent.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. This invention constructs a multi-component synergistic trapping agent composed of a copper matrix, flux, framework carrier and lattice activator, which significantly improves the recovery rate of platinum group metals, especially rhodium, in pyrometallurgical treatment of waste automobile exhaust purification catalysts, and reduces the smelting temperature required for pyrometallurgical treatment, thus significantly reducing energy consumption.

[0032] 2. This invention creatively integrates fluxing and slag-forming functions into borate, enabling it to form a highly efficient slag system while destroying the carrier. As a result, when treating waste catalysts by pyrometallurgy, there is no need to add traditional slag-forming agents (such as limestone, quartz, etc.), which reduces the types of raw materials and the amount of slag, and lowers the cost of subsequent slag treatment.

[0033] 3. In the preparation of the trapping agent by the present invention, each active component is pre-fixed on the skeleton carrier through a heat treatment step, forming composite particles with high strength and uniform composition. This not only prevents component segregation during transportation and feeding, ensuring the reproducibility of the reaction, but also enables the trapping agent to work synergistically as a whole in the furnace, greatly improving operational stability and reliability.

[0034] 4. The flux incorporated into the preparation of the collector in this invention forms a low-melting-point, low-viscosity slag with a large density difference and suitable interfacial tension compared to the copper-based alloy phase. After smelting, the slag phase and metal phase separate clearly and thoroughly; the slag phase is loose and brittle, with almost no metal beads being observed. This not only improves the recovery rate of the current recycling process but also significantly reduces the residual precious metal value in the waste residue, alleviating environmental pressure. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] The trapping agent comprises 50wt%~80wt% copper matrix, 5wt%~20wt% flux, 10wt%~30wt% framework carrier, and 1wt%~10wt% lattice activator. The copper matrix, flux, and lattice activator are loaded onto the surface of the framework carrier. The preparation method is as follows: the copper matrix, flux, framework carrier, and lattice activator are mechanically mixed (preferably ball-milled) into a homogeneous powder; under a reducing or inert atmosphere, the temperature is increased from room temperature to the target temperature at a rate of 1℃ / min~10℃ / min (preferably 3℃ / min~5℃ / min), held for 10min~60min, and then cooled to room temperature. The heat treatment temperature is higher than the melting point of the flux (borax) but lower than the melting point of the copper matrix; during this process, the molten flux acts as a binding medium, loading and fixing the copper matrix and lattice activator onto the surface and pores of the framework carrier, forming composite particles with high mechanical strength.

[0037] The copper matrix is ​​made of elemental copper or copper-based compounds, preferably metallic copper powder. The copper-based compounds are those that can be converted into metallic copper under reducing smelting conditions, such as cuprous oxide, copper oxide, and copper carbonate. The copper matrix is ​​the core component responsible for the trapping effect. The specific mechanism is as follows: copper melts at high temperatures, forming a continuous, high-density liquid metallic phase. Copper exhibits excellent miscibility and affinity with platinum, palladium, and rhodium (platinum group metal atoms or microparticles released from the spent catalyst support) in the high-temperature molten state, far exceeding its affinity with slag phase components (silicates and aluminates). Consequently, the platinum group metals spontaneously dissolve and diffuse into the molten copper. Ultimately, all platinum group metals are enriched in the copper matrix, forming a stable solid solution or intermetallic compound-copper-based alloy phase.

[0038] The flux is boric acid or borate, preferably borax, and more preferably anhydrous borax. Its main functions include lowering the melting point of pyrometallurgical smelting, destroying the carrier in the spent catalyst, and slag formation. Borates (such as borax) have a melting point of approximately 740°C and begin to melt much earlier than other components in the system during smelting, preferentially becoming the initial liquid phase. Furthermore, molten borates have a strong corrosive and dissolving ability against the γ-Al₂O₃ coating and cordierite carrier in the spent catalyst because they can break strong chemical bonds such as Al-O-Si and Al-O-Al, disrupting their stable crystal structure and thus completely exposing and releasing the platinum group metal particles, which facilitates their capture. In addition, borates react with the released SiO₂ and Al₂O₃ to form a low-melting-point, low-viscosity boroaluminosilicate slag. This slag has excellent fluidity and suitable surface tension, greatly promoting the sedimentation, aggregation, and separation of the denser copper-based alloy phase, reducing the loss of precious metal beads entrained in the slag.

[0039] The skeletal carrier is made of porous inorganic material; selected from at least one of porous alumina, porous silica, alumina-silica composite porous microspheres, expanded perlite, and pumice. The D50 of the porous inorganic material is 0.1mm~5mm (preferably 0.5mm~2mm), and the specific surface area is not less than 20m². 2 / g (preferably 50m) 2 / g~500m 2 The porous framework support has a porosity of not less than 50% (preferably 60%~90%) and a pore size distribution range of 10nm~1000nm. Its high specific surface area and three-dimensional network space greatly improve the reaction interface and mass transfer efficiency. During the preparation of the trapping agent, the copper matrix, flux, and lattice activator are loaded onto the large inner surface of the framework in the form of tiny particles, achieving high dispersion and immobilization of the active components and preventing their aggregation. In the pyrometallurgical recovery of platinum group metals, the molten flux and copper-based alloy liquid flow within the pores of the framework support under capillary force, reacting with the closely contacted spent catalyst particles, promoting a faster and more thorough reaction. The large specific surface area of ​​the framework support can physically adsorb gaseous or extremely fine platinum group metal oxides, enriching them near the copper liquid interface, thereby increasing the probability of trapping. In practical implementation, porous inorganic materials are divided into two types: those requiring synthesis and those formed naturally. Porous alumina, porous silica, and alumina-silica composite porous microspheres can be directly purchased commercially or prepared using conventional methods known in the art, including but not limited to sol-gel methods, precipitation methods, hydrothermal methods, or gas-phase methods. The above methods can effectively control the specific surface area, porosity, and pore size distribution of the material to meet the requirements of this invention, and are not specifically limited here. Expanded perlite and pumice are porous mineral materials formed by the high-temperature expansion of natural volcanic glass.

[0040] The lattice activator is made of tin, tin alloys or metal sulfides; by changing the physical properties of the copper matrix or inducing new reaction pathways, the efficiency for difficult-to-recover metals (such as rhodium) is specifically improved.

[0041] The copper matrix, flux, framework carrier, and lattice activator work synergistically to efficiently capture platinum group metals while reducing the temperature and time required for pyrometallurgical processes.

[0042] The above-described collector, used as a collector for the pyrometallurgical recovery of platinum group metals from spent catalysts, involves the following specific steps:

[0043] S1. The precipitating agent, reducing agent and binder are added to the waste catalyst after pulverization and mixed and then formed into pellets;

[0044] The amount of the trapping agent is 5 wt% to 15 wt% of the spent catalyst;

[0045] The reducing agent is a carbonaceous reducing agent, such as coal powder, coke powder, or graphite powder, and its dosage is 2wt% to 8wt% of the waste catalyst. During the high-temperature smelting process, the reducing agent creates and maintains a reducing atmosphere to prevent the metal (especially the copper matrix) from being oxidized and ensure that it exists in a metallic state, thereby effectively capturing platinum group metals. The reducing flux, such as borax, may react with carbon at high temperatures to generate more reactive boron, further enhancing the reducing environment.

[0046] The binder is an organic binder, and its dosage is 1wt%~5wt% of the mixture of the waste catalyst, scavenger, and reducing agent. At room temperature, the binder binds the mixed powder together through physical or chemical action, giving the raw material lumps sufficient cold mechanical strength; preventing them from being blown apart by the airflow when entering the furnace, causing material loss and environmental pollution; and ensuring that the lumps do not prematurely pulverize in the initial stage of heating in the furnace, thus enabling uniform heating and reaction. Sodium carboxymethyl cellulose is preferably used as the organic binder, as it leaves no residue after combustion, avoiding the introduction of additional slag impurities.

[0047] S2. Under a reducing atmosphere, smelting is carried out at 1200℃~1350℃ (preferably 1250℃~1300℃) to form a copper-based alloy phase rich in platinum group metals and a slag phase.

[0048] S3. Separate the copper-based alloy phase and the slag phase, wherein the copper-based alloy phase is enriched with platinum group metals.

[0049] In specific implementation, platinum group metals can be further extracted and refined from the copper-based alloy phase. The separated copper-based alloy phase can be further processed by various methods known in the art to extract and refine platinum group metals, such as first removing most of the copper by electrolytic refining or acid leaching to obtain a high-grade platinum group metal concentrate; the concentrate can be dissolved in aqua regia or hydrochloric acid-chlorine system and transferred into a solution; the mixed solution after dissolution can be separated and purified by solvent extraction, or by traditional selective precipitation; finally, high-purity platinum, palladium, and rhodium products are obtained by calcination or reduction.

[0050] Example 1

[0051] Preparation of the trapping agent:

[0052] The microspheres consist of 65 wt copper powder, 10 wt flux (borax), and 10 wt% matrix carrier (alumina-silica composite porous microspheres, D50=1.2mm, specific surface area 380m²). 2 Weigh out the raw materials: / g, porosity=82%, most probable pore size=25nm) and 5wt% lattice activator (tin powder);

[0053] After the raw materials are mixed, they are heated to 800°C at 5°C / min under a hydrogen atmosphere and kept at that temperature for 30 minutes. After cooling, they are crushed and sieved to 1mm~3mm to obtain the trapping agent.

[0054] Example 2

[0055] Preparation of the trapping agent:

[0056] The mixture consists of 60 wt% copper powder, 15 wt% flux (borax), and 20 wt% skeleton carrier (porous alumina microspheres, D50=0.8mm, specific surface area of ​​280m²). 2 Weigh out the raw materials: (g, porosity = 75%, most probable pore size = 15nm) and 5wt% lattice activator (ferrous sulfide);

[0057] After the raw materials are mixed, they are heated to 800°C at 5°C / min under a hydrogen atmosphere and kept at that temperature for 30 minutes. After cooling, they are crushed and sieved to 1mm~3mm to obtain the trapping agent.

[0058] Example 3

[0059] Preparation of the trapping agent:

[0060] The mixture consists of 70 wt% copper powder, 10 wt% flux (borax), and 15 wt% skeleton carrier (natural expanded perlite, D50=1.5mm, specific surface area 45m²). 2 Weigh out the raw materials: / g, porosity=90%, main pore diameter 1μm~50μm) and 5wt% lattice activator (tin powder);

[0061] After the raw materials are mixed, they are heated to 800°C at 5°C / min under a hydrogen atmosphere and kept at that temperature for 30 minutes. After cooling, they are crushed and sieved to 1mm~3mm to obtain the trapping agent.

[0062] Example 4

[0063] Preparation of the trapping agent:

[0064] The mixture consists of 62% wt copper powder, 13 wt% flux (borax), and 20 wt% skeleton carrier (porous silica, D50=0.5mm, specific surface area of ​​550m²). 2 Weigh out the raw materials: / g, porosity=85%, most probable pore size=8nm) and 5wt% lattice activator (tin powder);

[0065] After the raw materials are mixed, they are heated to 800°C at 5°C / min under a hydrogen atmosphere and kept at that temperature for 30 minutes. After cooling, they are crushed and sieved to 1mm~3mm to obtain the trapping agent.

[0066] Example 5

[0067] Preparation of the trapping agent:

[0068] The mixture consists of 65 wt copper powder, 12 wt flux (borax), and 15 wt% skeleton carrier (natural pumice particles, D50=2.0mm, specific surface area of ​​5m²). 2 Weigh out the raw materials: / g (porosity = 85%, main pore diameter 10μm~200μm) and 5wt% lattice activator (tin powder);

[0069] After the raw materials are mixed, they are heated to 800°C at 5°C / min under a hydrogen atmosphere and kept at that temperature for 30 minutes. After cooling, they are crushed and sieved to 1mm~3mm to obtain the trapping agent.

[0070] Example 6

[0071] Preparation of the trapping agent:

[0072] The mixture consists of 80 wt% copper oxide powder, 10 wt% flux (borax), and 5 wt% skeleton carrier (alumina-silica composite porous microspheres, D50=1.2mm, specific surface area 380m²). 2 Weigh out the raw materials: / g, porosity=82%, most probable pore size=25nm) and 5wt% lattice activator (tin powder);

[0073] After the raw materials are mixed, they are heated to 800°C at 5°C / min under a hydrogen atmosphere and kept at that temperature for 30 minutes. After cooling, they are crushed and sieved to 1mm~3mm to obtain the trapping agent.

[0074] Comparative Example 1

[0075] The trapping agent in this comparative example consists of pure copper powder.

[0076] Comparative Example 2

[0077] The difference between this comparative trapping agent and Example 1 is that it does not contain a lattice activator. The specific composition is: 70% copper powder, 10% borax, and 20% porous alumina-silica composite microspheres. Other conditions and preparation methods are the same as in Example 1.

[0078] Comparative Example 3

[0079] The difference between this comparative trap and Example 1 is that it does not contain a flux. The specific composition is: 75% copper powder, 20% porous alumina-silica composite microspheres, and 5% tin powder. Other conditions and preparation methods are the same as in Example 1.

[0080] Comparative Example 4

[0081] The difference between this comparative trap and Example 1 is that it has no skeleton carrier. The specific composition is: 75% copper powder, 20% borax, and 5% tin powder. Other conditions and preparation methods are the same as in Example 1.

[0082] Comparative Example 5

[0083] The difference between this comparative trapping agent and Example 1 is that the components of the trapping agent are only mechanically mixed and not heat-treated, and the composition is the same as that of Example 1.

[0084] Comparative Example 6

[0085] The difference between this comparative trapping agent and Example 1 is that the skeleton carrier uses a non-porous, dense kaolinite filler. The specific composition is: 65%wt copper powder, 20wt% flux (borax), and 10wt% dense kaolinite filler (alumina-silica composite porous microspheres, D50=1.0mm, specific surface area 8m²). 2 / g (porosity less than 10%) and 5wt% lattice activator (tin powder), with other conditions and preparation methods consistent with Example 1.

[0086] Example 7

[0087] The trapping agents from Examples 1 to 6 and Comparative Examples 1 to 5 were applied to the pyrometallurgical recovery of platinum group metals from spent catalysts, and the specific methods are as follows:

[0088] S1, take 100g of waste catalyst (platinum Pt 1320g / t; palladium Pd 917g / t; rhodium Rh 298g / t), crush it to 100 mesh and pass it through a sieve, add 15g of scavenging agent, 4g of coal powder as a reducing agent, 3g of sodium carboxymethyl cellulose (CMC) as a binder, add an appropriate amount of water and mix evenly, press it into Φ15mm lumps, and dry it at 120℃ for 2 hours;

[0089] S2, place the lump in a corundum crucible and melt it in a box-type resistance furnace at 1250°C under a hydrogen atmosphere for 120 minutes.

[0090] S3. After cooling, the waste residue phase and the copper-based alloy phase are physically separated. The contents of platinum (Pt), palladium (Pd), and rhodium (Rh) in the copper-based alloy phase are analyzed by ICP-OES, and the recovery rate is calculated.

[0091] Comparative Example 7

[0092] The specific method for pyrometallurgical recovery of platinum group metals from spent catalysts is as follows:

[0093] S1, take 100g of waste catalyst (platinum Pt 1320g / t; palladium Pd 917g / t; rhodium Rh 298g / t), crush it to 100 mesh and sieve it, add 15g of the trapping agent prepared in Example 1 and 4g of coal powder as reducing agent, add an appropriate amount of water and mix evenly, press it into Φ15mm lumps, and dry it at 120℃ for 2 hours;

[0094] S2, place the lump in a corundum crucible and melt it in a box-type resistance furnace at 1250°C under a hydrogen atmosphere for 120 minutes.

[0095] S3. After cooling, the waste residue phase and the copper-based alloy phase are physically separated. The contents of platinum (Pt), palladium (Pd), and rhodium (Rh) in the copper-based alloy phase are analyzed by ICP-OES, and the recovery rate is calculated.

[0096] Recovery rate = M1 / M2, where M1 and M2 are the contents of the corresponding platinum group metals in the copper-based alloy phase and the spent catalyst, respectively. The results are shown in Table 1.

[0097] Table 1

[0098]

[0099] In Example 7 of this invention, the trapping agents prepared according to Examples 1 to 6 all maintained a stable recovery rate of over 99% for platinum, palladium, and rhodium. This demonstrates that the trapping agent of the quaternary synergistic system proposed in this invention has high reliability and universality.

[0100] The skeleton carriers in Examples 1, 2, and 4 are made of artificially synthesized porous materials, which are compared with the skeleton carriers in Examples 3 and 5, which are made of natural porous minerals. It can be seen that the recovery rate of the examples using high specific surface area artificial microspheres is slightly better than that of the examples using perlite and pumice.

[0101] Compared with Example 1, which uses copper powder, Example 6, which uses a copper oxide matrix, has a slightly lower recovery rate. This is because copper oxide needs to be reduced to metallic copper in the furnace first, which consumes a small amount of reducing agent and has a slight kinetic lag.

[0102] Compared with Example 1, Comparative Example 2, which lacked a lattice activator, showed lower recovery rates for all platinum group metals, with a significantly lower rhodium recovery rate. This is because Comparative Example 2 lacked a tin activator. The copper melt had a high melting point, high viscosity, and poor fluidity, preventing it from fully penetrating the micropores of the carrier to contact and alloy with the encapsulated, chemically inert rhodium atoms. The addition of tin, by forming a low-melting-point eutectic, fundamentally improved the physical properties of the trapping phase, thereby increasing rhodium recovery efficiency.

[0103] Compared with Example 1, Comparative Example 3, which uses no flux, showed a significantly lower recovery rate of platinum group metals. This is because, without flux, the high-melting-point cordierite and alumina support cannot be broken down. The platinum group metals are firmly locked in the solid support and cannot be released. Simultaneously, the system cannot form a fluid slag phase, resulting in ineffective slag-metal separation.

[0104] Compared to Example 1, Comparative Example 4, which lacks a framework-free support, showed significantly lower recovery rates of platinum group metals. This is because the lack of a high-surface-area framework resulted in uneven dispersion of components such as copper powder and flux in the material, leading to easy aggregation. The reaction interface decreased drastically, resulting in low mass transfer efficiency. This led to incomplete support cell disruption, incomplete release of platinum group metals, and a reduced probability of contact between the released metals and the molten copper.

[0105] In Comparative Example 5, the components of the trap were mechanically mixed without heat treatment. Although its recovery rate of platinum group metals (especially rhodium) was better than other comparative examples, it was still lower than that of Example 1, which underwent heat treatment. This is because physical mixing cannot achieve a strong bond between the components, easily leading to component segregation and inconsistent chemical compositions in each trap particle. The heat treatment step, through the melting and re-solidification of borax, loads the active components onto the framework, ensuring the homogeneity and stability of the reaction precursor, thus resulting in more robust recovery performance.

[0106] Compared to Example 1, Comparative Example 4, which uses a non-porous framework carrier, showed significantly lower recovery rates of platinum group metals compared to Example 1. This is because dense kaolinite has a smooth surface with very few pores. It is essentially an inert filler and cannot provide effective loading and dispersion. The active components (copper, borax, tin) simply adhere to its surface and are easily separated and aggregated during pelletizing and smelting, leading to a sharp reduction in the effective reaction interface and consequently a significant decrease in recovery efficiency.

[0107] Compared with Example 7, Comparative Example 7, which removed the binder during pyrometallurgical recovery, showed a slightly lower recovery rate for platinum group metals compared to Example 7. This is because the binder-free clumps have low strength and pulverize before reaching the reaction temperature when heated in the furnace; fine powder is carried out of the reaction zone by the furnace airflow, causing physical losses; and the carried-away powder contains unreacted trapping agents and spent catalysts, directly leading to a decrease in recovery rate.

[0108] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A collector for recovering platinum group metals from spent catalysts, characterized in that, The trapping agent includes a copper matrix, flux, framework carrier, and lattice activator: In the aforementioned trapping agent, a copper matrix, flux, and lattice activator are loaded on the surface of the skeletal carrier; The copper matrix is ​​made of elemental copper or a copper-based compound. The flux is boric acid or borate; The skeleton carrier is made of porous inorganic material; The lattice activator is tin, a tin alloy, or ferrous sulfide; The collector is used as a collector for pyrometallurgical recovery of platinum group metals from waste catalysts. During pyrometallurgical recovery of platinum group metals, the molten flux and the alloy liquid of the copper matrix flow in the pores of the skeleton carrier under the action of capillary force and react with the waste catalyst particles in close contact. The weight percentages of each component in the raw material of the trapping agent are as follows: Copper matrix: 50%~80%; Flux: 5%~20%; Skeleton carrier: 10%~30%; Lattice activator: 1%~10%.

2. The collector for recovering platinum group metals from spent catalysts according to claim 1, characterized in that, The porous inorganic material is selected from at least one of porous alumina, porous silica, alumina-silica composite porous microspheres, expanded perlite, and pumice.

3. The collector for recovering platinum group metals from spent catalysts according to claim 2, characterized in that, The porous inorganic material has a D50 of 0.1 mm to 5 mm and a specific surface area of ​​not less than 20 m². 2 / g, porosity not less than 50%.

4. The scavenger for recovering platinum group metals from spent catalysts according to claim 2, characterized in that, The porous inorganic material has a D50 of 0.5 mm to 2 mm and a specific surface area of ​​50 m². 2 / g~500m 2 / g, with a porosity of 60%~90%; pore size distribution range of 10nm~1000nm.

5. The method for preparing the scavenger for recovering platinum group metals from spent catalysts according to any one of claims 1 to 4, characterized in that, The preparation method specifically involves: mechanically mixing the copper matrix, flux, framework carrier, and lattice activator into a uniform mixed powder; and performing heat treatment under a reducing or inert atmosphere at 600℃~900℃.

6. The method for preparing a scavenger for recovering platinum group metals from spent catalysts according to claim 5, characterized in that, The heat treatment specifically involves heating from room temperature to the target temperature at a rate of 1℃ / min to 10℃ / min under a reducing or inert atmosphere, holding at that temperature for 10min to 60min, and then cooling to room temperature.

7. The application of the scavenger for recovering platinum group metals from spent catalysts according to any one of claims 1 to 4, characterized in that, The collector is used as a collector for platinum group metals in the pyrometallurgical recovery of waste catalysts.

8. The application of the scavenger for recovering platinum group metals from spent catalysts according to claim 7, characterized in that, The specific steps of the pyrometallurgical method for recovering platinum group metals from spent catalysts are as follows: After pulverization, the precipitant, reducing agent, and binder are added to the waste catalyst, mixed, and agglomerated. Under a reducing atmosphere, smelting is carried out at 1200℃~1350℃ to form a copper-based alloy phase and a slag phase rich in platinum group metals; The copper-based alloy phase and the slag phase are separated, wherein the copper-based alloy phase is enriched with platinum group metals.

9. The application of the scavenger for recovering platinum group metals from spent catalysts according to claim 8, characterized in that, The amount of the trapping agent is 5 wt% to 15 wt% of the spent catalyst; The reducing agent is a carbonaceous reducing agent, and its dosage is 2wt%~8wt% of the spent catalyst; The binder is an organic binder, and its dosage is 1 wt% to 5 wt% of the mixture of the waste catalyst, the scavenger and the reducing agent.

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